Sound-producing and sound-reproducing apparatus



June 16, 1942. E, w. KELLOGG 2,286,742 I SOUND-PRODUCING AND SOUND-REPRODUCING APPARATUS Filed March 1, 1941 YIIIIIII/l/I.

Zmventor Patented June 16, 1942 SOUND-PRODUCING AND SOUND-REPRO- DUCING APPARATUS Edward W. Kellogg, Moorestown, N. J., assignor to Radio Corporation of America, a corporation of Delaware I Application March 1, 1941, Serial No. 381,220

9 Claims.

This invention relates to combined sound-producing and sound-reproducing apparatus, and more particularly to the sound-distribution system of a combined electric piano and radio receiver and/or electric phonograph.

In a conventional electric piano with which is incorporated a radio receiver or electric phonograph, it is customary to mount the loudspeaker on the sounding board which acts as a coupled resonator, or else in the panel under the keyboard. In such an arrangement, the sound does not come directly to the ears of the person playing the piano, and some reverberation effect is present. Even with this loudspeaker arrangement, however, electric pianos have been criticised for the sudden attack of the tone, that is, the sharpness withwhich the notes begin. Another objection to conventional electric pianos of this type is that feedback troubles are encountered by reason of the fact that the loudspeaker cones are usually mounted close to the strings.

While the location of the sound source near the floor is not objectionable for piano music, this is by no means the most favorable location for a loudspeaker for radio reception. It is very desirable for radio reception that the loudspeaker be near the level of the listeners ears andthat it shall radiate horizontally in order that the high frequency components of sound may not be lost and the clarity of diction thereby sacrificed. On the other hand, locating the loudspeaker in the upper part of the piano cabinet and directed horizontally would be most objectionable tothe person playing the piano, who has little choice of position. It would be entirely too close for pleasure since the piano music sound would reach the pianists ears with no reverberation, and with an even worse sharp attack than with the loudspeaker located close to the floor.

The primary object of my present invention is to provide an improved combination electric piano and sound-reproducing apparatus which will be free from the foregoing objections, and wherein the most desirable listening conditions are produced for both piano music and for radio reception or phonograph reproduction.

More particularly, it is an object of mypresent invention to provide, in a combined electric .piano and sound-reproducing apparatus, a novel sounddistribution system forthe loudspeaker thereof whereby the. sudden attack" of the tone will be less conspicuous and wherein the tendency to feedback is greatly minimized. 1

Another object of my present invention is to provide an improved combination electric piano and sound-reproducing apparatus which may be readily conditioned for suitably directing the sound waves emanating from the loudspeaker thereof in accordance with whether the piano is to be actuated to produce sounds locally, or whether the sound-reproducing apparatus is to be actuated to reproduce sounds originating in a radio receiver or phonograph.

It is a further object of my invention to provide a loudspeaker for use in a combination piano and radio receiver which will radiate the, high frequency sounds approximately horizontally from a source several feet from the floor when the instrument is in use for radio reception, but will direct the high frequency sounds away from the pianist and not directly toward anylisteners when the loudspeaker is serving to radiate the piano music. I

Still another object of my present invention is to provide an improved combination electric piano and sound-reproducing apparatus as aforesaid which can be readily manipulated to produce the desired effects.

It is also an object of my present invention to provide an improved combination electric piano and sound-reproducing apparatus as aforesaid which'is relatively simple in construction and highly eflicient in use.

According to my present invention, instead of mounting the loudspeaker cone in the panel below the keyboard of the piano, I preferably employ a somewhat smaller than conventional cone and mount it above the keyboard in a manner such that the higher frequencies are radiated from the front of the cone, while. the back of the cone is connected to a suitable horn adapted to reproduce particularly the lower frequencies.

Such a sound radiating system is, in principle, in accordance with that described in U. S. Patent to Olson No. 2,224,919. In this speaker, the front of the cone is freely exposed as in the usual baflie type of radio loudspeakers, while the horn structure which is coupled to the back of the cone or diaphragm serves to improve the radiation of low frequency tones. The horn may be so constructed as to act as a low-pass acoustic filter. It serves to increase the radiation of low frequency sounds and to improve the efliciency of the loudspeaker. By confining the low frequency waves within the horn passagesthe horn also reduces the likelihood of transmitting vibrations to the piano strings and thus producing a feed back effect when the loudspeaker is serving to produce piano music..

Preferably, the cone is arranged to face the front of the piano cabinet to radiate sound through an opening in the front wall thereof. An opening is also provided in the top wall of the cabinet and enough space is provided between the cone and the front cabinet wall to pivotally accommodate a reflector. This reflector is so connected with the keyboard cover that, when the cover is down over the keys, the reflector occupies a horizontal position external to the path between the loudspeaker cone and the front wall opening, a hinged cover then closing the top wall 4 opening, so that sounds radiated by the loudspeaker pass out directly through the front wall opening to the exterior of the cabinet. Onthe other hand, when the keyboard cover is raised to expose the piano keys, the reflector'is raised to an inclined position in front of the loudspeaker cone for the purpose of deflecting the sounds radiated thereby in an upward direction through the opening in the top of the piano cabinet, the cover in the top wall'being then in raised position. The reflecting surface of the reflector is not necessarily flat, but maybe designed to scatter the. sound. The result will be that the higher frequency components of the sound will be heard only after some reflection'from the room ceiling and walls, thus adding a reverberationeffect as compared with listening to sounds radiated directly by the cone.

When the instrument is in use for radio reception or-phonograph reproduction, the key-- board cover is closed and the reflector is inits lower position, so that the listener will have.

the benefit of direct sound from the loudspeaker, as is generally preferred for speech. n the other hand, when the piano is being played.

the keyboard cover is, of necessity, open, the reflector is in its raised position, and the sounds emanating from the loudspeaker are directed upwardly through the top wall opening. or course, the listener may also cause the sounds emanating from the loudspeaker to pass up toward the ceiling when the radio or phonograph is reproducingmus'ic, if he prefers, so as toen- Joy the benefit of indirect sound, by simply raising the keyboard cover.

The novel features that I consider characteristic of my invention are set forth with particu-.

larit'y in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as adclitional objects and advantages thereof, will best be understood from the following description of one embodiment thereof, when read in connection with the accompanying drawing, in which Figure 1 is-a transverse sectional view of a combined electric piano and radio receiver ac-.

cording to my present invention and arranged to direct the sound waves upwardly toward the ceiling, and

Figure 2 is a similar view, but showing the parts arranged sov as to direct the sound forwardly. I Referring more particularly to the drawing. wherein similar reference characters indicate corresponding parts throughout, there is shown a.

piano casing I having a front wall 3 provided with an opening 5 which may be covered by a suitable grille I in conventional manner. The

cabinet I also includes a top wall 9 havingan opening Il therein which may be covered by a suitable grille l3. The top wall 9 also has pivotally connected thereto a cover I5 which is adapted to close the opening II when in lowered position and to .expose the opening II when in Within the cabinet I, and preferably above the sounding board (not shown), is a cone loudspeaker I9 having a conical diaphragm 2| which faces forwardly toward the front wall opening 5, a reflector 23 being pivotally mounted in the casing or cabinet I between the cone 2| and the front wall 3. The cabinet I also houses a suitable sound-reproducing apparatus, such as a radio receiver 25 having one or more control knobs 21 on the front wall 3, or an electric phonograph, the loudspeaker I9 being operatively associated with both the electric piano and the sound-reproducing apparatus.

Pivotally connected at one end to the reflector 23 and at its other end to a bracket v29 which is secured to the coverI5 is alink member 33 which is so coupled to the cover I5 and the reflector 23 that they may move. in unison to and from the two positions shown in Figs. 1 and 2. The keyboard cover I! has secured thereto a lever 35 which is coupled to a lever 31, secured to the reflector 23, by a link 39. The link mechanism 35, 31, 39 is so related to the keyboard I1 and the reflector 23 that, when the keyboard cover I1 is lowered to the-position shown in Fig, 2 in order to cover the keys I8, the reflector 23 will be lowered to its horizontal position external to the path between the loudspeaker cone 2I and the front wall opening 5, the link 33 at the same time pulling the cover I5 down into closed position over the opening" I I. Sound waves radiated by the loudspeaker 2I can then pass'out of the cabinet I only forwardly through the front wall opening 5. 0n the other hand, when the keyboard I1 is raised to the position shown in Fig. .1, the link 39, in cooperation with the levers 35 and'3l, raises the reflector 23 to the inclined position of Fig. 1 to block off the path between the cone 2| and the front wall opening 5. At the same time, the link 33 raises the cover I5 to the position shown in Fig. 1 in order to expose the opening II, and sound waves emanated by the ,loudspeaker are then reflected up- 'wardly through the opening II by the reflec- From the. foregoing description, it will be obfront surface of the cone 2| will pass either directly out through the front wall opening 5, or upwardly through the top wall opening II for subsequent reflection from the ceilingand q walls of the room, thereby adding a reverberaberation effect is desirable when music is being tion effect ascompared with listening to sounds radiated directly by the cone 2I. This rover-- produced by playing the piano, especially in view of the unavoidable close proximity of the person playing the piano, and the instrument is automatically conditioned therefor when .the piano keyboard I1 is raised. When, however, speech is being reproduced by the radio receiver or phonograph 25, and it is preferable to have the sound pass directly and without reflectionandreverberation to the listener, who would then normally be sitting further away, the piano keyboard cover I! is lowered to the position of Fig. 2, and

' the sounds will pass directly out through the front wall opening 5. To the back on rear surface of the cone 2| is preferably coupled a long, folded horn of the type shown. for example, in the above identified Olson patent, the latter horn being particularly adapted to reproduce the low frequencies and directing the sound waves forwardly into the room through an opening 4| in the lower part of the cabinet I. The latter horn is conveniently arranged within the cabinet I and is constantly coupled to the rear surface of the cone 2| regardless of the position of the reflector 23.

Although I have shown and described but one embodiment of my invention, it will be apparent to those skilled in the art that many other modifications thereof, as well as changes in the one described herein, are possible. For example, if desired, the movement of the keyboard cover H from one position to the other may be made to actuate a suitable switch or other mechanism for controlling the energy delivered to the loudspeaker I9 by either the electric piano or the sound reproducing device 25. Also, instead of depending entirely on a reflector to change the direction of radiation from the front of the diaphragm, the entire loudspeaker may be turned to either of two positions, provision being made to maintain suitable coupling between the back of the cone and the horn, for both positions of the speaker unit. Other similar modifications will, no doubt, readily suggest themselves to those skilled in the art. I, therefore, do not Wish to be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In an electrical sound producing instrument including a loudspeaker, a cabinet in which said loudspeaker is housed, said cabinet including a top and a front wall each of which has an opening therein through which sound waves emitted by said loudspeaker may pass to the exterior of said cabinet, a cover hingedly connected to said top wall and adapted to be swung to and from open and closed positions relative to the opening in said top wall, a reflector hingedly mounted in said cabinet and arranged for swinging movement into and out of two positions in one of which said reflector is outside of the path between said loudspeaker and the opening in said front wall and in the-other of which said reflector is interposed in said path to shut ofi communication between said loudspeakerand said front wall opening and to direct sound waves emitted, by said loudspeaker'toward said top wall opening, and means interconnecting said cover and said reflector for movement in unison such that, when said cover is swung to open position relative to said top wall opening,

. said reflector is moved to its second-named position, and when said cover is swung into closed relation with said top wall opening, said reflector is moved to its first-named position.

2. The invention set forth in claim -1 characterized by the addition of means on said cabinet for actuating said interconnecting means whereby to move said cover and reflector into one or the other of said positions. I

3. In a combined electric piano and electrical sound reproducing apparatus, the combination of a cabinet includinga top and a front wall,

each of said walls having an opening therein through which sound waves emanating from a source within said cabinet may pass out to the exterior of said cabinet, a loudspeaker within said cabinet operatively associated with both said piano and said sound reproducing apparatus and adapted to emit sound waves, and selectively operable means for causing the sound waves emitted by said loudspeaker in response to said piano to pass out through the opening in said top wall and for causing the sound waves-emitted by said loudspeaker in response to said sound reproducing apparatus to pass out through said other opening.

10 4. In a combined electric piano and electrical sound reproducing apparatus, the combination of a cabinet including a top and a front wall, each of said walls having an opening therein through which sound waves emanating from a source within said cabinet may pass out to the exterior of said cabinet, a loudspeaker within said cabinet operatively associated with both said piano and said sound reproducing apparatus and adapted to emit sound waves, a cover 2 hingedly connected to said top wall and adapted to be swung to and from open and closed positions relative to said top wall opening, a reflector hingedly' mounted in said cabinet and arranged for swinging movement into and out of two positions in one of which said reflector is outside of the path between said loudspeaker and said front wall opening and in the other of which said reflector is interposed in said path to shut on communication between said loudspeaker and said front wall opening and to vdirect sound waves emitted by said loudspeaker toward said top wall opening, and selectively operable means for moving said cover to open position and said reflector to its second-named position when said loudspeaker is to be actuated by said piano and for moving said cover to-closed position and said reflector to its first-named position when said loudspeaker is to be actuated by said sound-reproducing apparatus. 7

5. The invention set forth in: claim 4 characterized in that said piano includes a 'hinged key cover, characterized further by the addition of a link member pivotally connected to both said top wall cover and said reflector whereby to couple said top wall cover and reflector for movement in unison, and characterized still further by the addition of link mechanism coupling said key cover and said reflector for movement in unison, said link mechanism and link member V being so constructed and arranged relative to said key cover, said top wall cover and said reflector that, when said key cover is raised to expose the piano keys, said'link mechanism and link member will cause said reflector to .move

into its second-named position and said top wall cover to open, and when said key cover is lowered to cover said keys, said link mechanism and link member will cause said reflector to move into its first-named position and said top wall cover to 61) close. l

6. The invention set forth in claim 4 characterized in that said loudspeaker includes a diaphragm, and characterized further in that said top and front wall openings are associated 65 with only the front surface of said diaphragm.

7. The invention set forth in claim 4 characterized in that loudspeaker includes a diaphragm, characterized further in that said top and front wall openings are associated with only the front surface of said diaphragm, and characterized still further by the addition of a horn in said cabinet coupled to the rear surface of said diaphragm, said horn being constantly in coupled relation to said rear surface.

8. In a combined electric piano and electrical sound reproducing apparatus all housed in a single cabinet, a loudspeaker located in the upper part of said cabinet and including a diaphragm, said cabinet having an opening. therein in one wall thereof adjacent another part of said cabinet and said piano including a plurality of strings, means coupling the back of said diaphragm to said opening and providing an acousticpassage for conducting from said diaphragm to said opening sound waves radiated by the back of said diaphragm, said means being constructed and arranged to shield said piano strings from sound waves radiated by said diaphragm, and means for altering the direction of sound waves radiated from the front of said diaphragm.

9. In a combined electric piano and electrical sound reproducing apparatus all housed in a single cabinet, a loudspeaker located in the upper part 01. said cabinet and operatively a50- ciated with both said piano and said sound reproducing apparatus, said loudspeaker including a diaphragm adapted to directively radiate high frequency sounds near the top of said cabinet, said cabinet having an opening therein in another part thereof, means coupling the back of said diaphragm to said opening and providing an acoustic passage for conducting from said diaphragm to said opening low frequency sounds radiated by said diaphragm, and means for altering the direction of radiation of said high frequency sounds. l

' EDWARD W. KELLOGG. 

